The present system relates generally to integrated circuits and associated methods and particularly, but not by way of limitation, to a voltage buffer and associated methods.
Integrated circuits often require substantially constant bias voltages. A precision voltage reference circuit, such as a bandgap voltage reference, may be used to generate a precise voltage for use by other circuits. However, such precision voltage reference circuits often lack the ability to provide a stable voltage over a wide range of load currents being drawn by one or more of these other circuits using the precision reference voltage. Moreover, when more than one load circuit shares the same voltage reference, the collective load capacitance imposed by such circuits on the voltage reference can be substantial. Furthermore, some of these load circuits may involve transistor switching, which can result in large current spikes being drawn from the voltage reference. Others of these load circuits may involve coupling and decoupling capacitors to and from the voltage reference. This can also result in large current spikes being drawn from the voltage reference. In order to provide a stable reference voltage over a variety of circuit conditions, there is a need for a voltage buffer circuit having a low output impedance and a large current drive capability.